public class spisok {
	
		public element head = null;
		
		public void del_beg(element elem){
			if(head == null){
				head = elem;
			}
			else {
				head=null;
				elem=null;
				}
		}
		
		public void del_end(element elem){
			if(head == null){
				head = elem;
			}
			else {
				element cur = head;
			while(cur.next.next != null){
				
				cur = cur.next;
			}
			cur.next=null;
			}
		}
		
		public void bubble_sort(element elem){
			boolean swapped = true;
			int j = 0;
			if(head == null){
				head = elem;
			}
			else {
				element cur = head;
			while(cur.next != null){
				do{
					if(j!=0){
						j=0;
						cur = head;
					}
					swapped = false;
				if(cur.i>cur.next.i){
					j++;
				int tmp = cur.i;
				cur.i = cur.next.i;
				cur.next.i = tmp;
				swapped = true;
				}}while(swapped);
				cur = cur.next;	
			}}}
		
		public void add_after(element elem ,int elem1){
			if(head == null){
				head = elem;
			}
			else {
				element cur = head;
			while(cur.next != null){
				if(cur.i == elem1){
					elem.next=cur.next;
					cur.next=elem;
					return;
				}
				cur = cur.next;
			}
			}}
		
		public void addstart(element elem){
			if(head == null){
				head = elem;
			}
			else{
				elem.next = head;
				head =  elem;
			}
		}
		
		public void add_end(element elem){
		if(head == null){
			head = elem;
		}
		else {
			element cur = head;
			while(cur.next != null){
				cur = cur.next;
			}
			cur.next = elem;
			
		}
		}
		
		public String toString(){
			StringBuffer sb= new StringBuffer();
			sb.append("[");
			element current = head;
			while (current != null){
				sb.append(current.i + " ");
				current = current.next;
			}
			sb.append("]");
			return sb.toString();
		}
	
}
